1. Field of the Invention
The present invention relates to a laying tube for producing wire windings from continuously introduced essentially straight wire material.
2. Description of the Related Art
As is well known in the art, the wear to which laying tubes for windings in wire trains are subjected is substantial.
Depending on the rolled dimensions and wire quality, the service life of laying tubes for windings is about two to five thousand metric tons. In the most unfavorable case, this means a service life of only three eight hour shifts when the production is 80 t/h in each line.
For replacing a worn out laying tube, the complete winding layer must be disassembled; this is very time-consuming and labor-intensive.
Accordingly, it has been repeatedly attempted to find solutions for increasing the service life of laying tubes for windings. For this purpose, European Patent Application EP 0 779 115 A1 proposes a laying tube which is composed of a first element which is driven so as to rotate and a second element which opens out in the shape of a bell. In this second element, a curved guide channel is provided. The wire material is conducted into this guide channel by means of a feeding tube which is mounted in the first element of the laying tube.
In an embodiment of this European Patent Application, the guide channel is formed by a groove which is provided in the outer surface of a hollow insert, wherein this insert is placed with fit in the opening portion of the laying tube. Consequently, the inner surface of the outer casing forms a portion of the wire guide channel.
The European Patent Application mentioned above further proposes to provide next to a first guide channel a second guide channel which is arranged symmetrically relative to the first guide channel. On the one hand, the second channel compensates the imbalance which is due to the centrifugal forces and, on the other hand, the second channel can be used as an alternative to the first guide channel when the first guide channel is worn out. In case of wear of the first channel, the wire is conducted into this alternative channel by rotating the feeding tube and placing it against the channel opening.
FIG. 4 of the European Patent Application referred to above shows an embodiment with four such guide channels which, consequently, means that the service life has been increased fourfold.